Known barrel coupling, “3-lug adapter” (“Soldier of Fortune”, No 6 1997, p. 26-30) for weapons is mounted to the barrel using three salient chuck jaws on the barrel.
Thread is usually used for mounting muzzle accessories to firearms barrel like guns and carabines (Device for silent and flameless shooting of 7.62-mm modernized Kalashnikov. Service manual, Voenizdat USSR Ministry of Defense. M. 1972)
Inability to mount the muzzle accessory to a properly unprepared gun barrel is the disadvantage of all the above mentioned kinds of barrel coupling for firearms.
In addition, there are difficulties with the barrel preparation for installing the muzzle accessory. Barrel loses its original factory form, which is not always acceptable.
The closest to the claimed solution is the barrel coupling to firearms, which includes the muzzle adapter to the barrel, separator with balls and clamping sleeve (Knight's Armament Airsoft 556 QDC/CQB Quick Detach Suppressor (14 mm CCW, BK)
In order to mount the mentioned above barrel coupling to firearm, the barrel has to be specially prepared, namely, special sockets have to be made for the balls or special adapter with sockets for the balls has to be installed on a thread.